This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The infection of Asian macaque monkeys with simian immunodeficiency virus (SIV) and SIV/HIV chimeric viruses (SHIVs) serves as an important animal model for studying the pathogenesis of HIV infection and AIDS. In addition, this model provides a challenge system for evaluating the efficacy of vaccines and antiretroviral agents designed to prevent infection or AIDS in humans. We have designed several molecular probes for localizing viral RNA in tissues of monkeys infected with various isolates and clones of SIV and SHIV. These probes are used to measure the quantity and distribution of infected cells in the tissues of infected monkeys. We also have probes that hybridize with target RNA or DNA sequences of several other viral pathogens, including HIV, SRV-1, CMV, SV40, EBV, Herpes saimiri, and parvovirus.